Theresa May won the support of her cabinet for a draft EU divorce deal but faces an anxious wait for a possible leadership challenge from angry Brexiteers.

The Prime Minister emerged from a marathon five-hour meeting of senior ministers yesterday evening saying there had been “collective decision” on the draft withdrawal terms, hinting at deep divisions within her government.

Earlier, she was put on notice by the Scottish Secretary David Mundell and the rest of the Scottish Conservative group at Westminster, who warned that they would not support a deal that fails to honour promises made to fishermen.

Theresa May said there had been a “long, detailed and impassioned debate” on the Brexit deal.

Speaking outside Number 10, the Prime Minister said: “I firmly believe that the draft withdrawal agreement was the best that could be negotiated and it was for the Cabinet to decide whether to move on in the talks.

“The choices before us were difficult, particularly in relation to the Northern Ireland backstop, but the collective decision of Cabinet was that the Government should agree the draft withdrawal agreement and the outline political declaration.”

Mrs May said: “This is a decisive step which enables us to move on and finalise the deal in the days ahead.

“These decisions were not taken lightly but I believe it is a decision that is firmly in the national interest.”

The Prime Minister announced she will make a statement to the House of Commons tomorrow and concluded: “I firmly believe, with my head and my heart that this is a decision which is in the best interests of the United Kingdom.”

Commenting on this evening’s Brexit statement by the Prime Minister, First Minister Nicola Sturgeon said:“It is obvious that the Prime Minister can barely unite her cabinet on this deal, and it is also increasingly clear that she will struggle to get a majority for it in Parliament.

“In these circumstances it is more important than ever that we are not faced with a false choice between a bad deal and no deal.

“No one should be effectively blackmailed into a choice between the frying pan or the fire.

“This proposed deal would be a bad one for Scotland, taking us out of a single market eight times the size of the UK market alone and posing a huge threat to jobs, investment and living standards.

”If this deal is indeed rejected by Parliament then the UK Government must return to the negotiating table to secure a better one.

“Our bottom line – short of continued EU membership – is continued, permanent membership of the single market and customs union.”

The chair of the European Research Group of Eurosceptic Tories, Jacob Rees-Mogg, wrote to Conservative MPs calling on them not to support Mrs May’s plan, arguing it would see the UK “hand over £39 billion to the EU for little or nothing in return”.

The deal is “unacceptable to unionists”, will “lock us into an EU customs union and EU laws”, and is “profoundly undemocratic”, said Mr Rees-Mogg.

Meanwhile, Arlene Foster, whose DUP party props up Mrs May’s minority administration in the Commons, warned the PM there would be “consequences” if her deal treats Northern Ireland differently from the rest of the UK.

The level of Brexiteer discontent has raised expectations of further letters of no confidence in Mrs May from Tory MPs, with a total of 48 needed to trigger a vote on her position.

Sources within Westminster said the delivery of letters to the chair of the backbench 1922 Committee Sir Graham Brady was “imminent”.

Mrs May described the debate around the famous Cabinet table as “long, detailed and impassioned”, in an apparent indication that her proposals had come under intense challenge from ministers.

But predicted resignations did not materialise, as Mrs May said ministers had come to a “collective decision” to back the document agreed by UK and EU negotiators in Brussels.

Speaking against the backdrop of boos and shouts from anti-Brexit campaigners on Whitehall, she said: “When you strip away the detail the choice before us is clear - this deal which delivers on the vote of the referendum, which brings back control of our money, laws and borders, ends free movement, protects jobs, security and our Union, or leave with no deal or no Brexit at all.”

The European Commission released the text of the withdrawal agreement - running to 585 pages - on its website as EU chief negotiator Michel Barnier prepared to hold a press conference in Brussels.

Commission president Jean-Claude Juncker wrote to European Council president Donald Tusk to inform him that “decisive progress” had been made in negotiations, allowing him to convene a summit of EU leaders.

The European Parliament’s Brexit co-ordinator, Guy Verhofstadt, welcomed the “positive progress” in negotiations, describing the draft agreement as “a milestone towards a credible and sustainable future relationship between the EU and the UK”.